I’m no expert on relationships but one thing I can tell you (more from a father’s perspective than from a peer’s) is that people make mistakes, especially with speech, since it’s so easy to say the wrong things at the wrong time. No doubt in my mind your ex regretted what he said but if you didn’t hear it from him later then he probably was too proud to admit it. If you want to stay in the relationship long-term with someone you care about in the future, you need to forgive on the small stuff. Because guess what? You’ll make mistakes too and it takes an equally mature person to forgive as well. Sorry for the advice since I know you’re usually the advice-giver on this blog but I believe it needs to be said since I hope it helps you in the future.